Improvement in processes for the m anufactu re of salt



S. B. HOWD.

Making Sal t.

Patented Oct. '10, 1854.

UNiTED STATES PATENT OFFICE.

SAMUEL I3. HOWD, OF SYRACUSE, NEW YORK, ASSIGNOR TO THOS. T. DAVIS,JAMES S. LEACH, AND RICHARD F. STEVENS.

IMPROVEMENT IN PROCESSES FORTHE MANUFACTURE OF SALT.

Specification forming part of Letters Patent No. l 1,80), dated October10, 1854.

and useful Improvement in the Process of- Manufacturing Salt; and I dohereby declare the following to be a full, clear, and exact descriptionof the process and of the construction, arrangement, and operation ofthe appa-.

tus connected therewith, reference being had to the annexed drawings,making] a part of this specification.

My invention embraces, first, a method of purifying brine; second, ofrunning steam machinery with steam generated in the art and process ofmanufacturing salt; third, of preventing the contact of salt withsteam-pipes used in evaporating brine in open vats.

I construct a steamboiler of wrought-iron in any form suitable forraising steam, having the well-known arrangements for the application offire. The boiler A is furnished with a steam-chamber, B, at its upperpart, which is connected with the boiler by two or more tubes, 0,passing upward through the bottom of the steam-chamber to near its upperpart.

D represents a large tube connected with the lower part of thesteam-chamber and passing into the lower part of the salting-vat at E.This tube or chamber extends to the opposite end of the vat, returns andpasses out near the point where it entered, giving a large extent oftube or chamber with the vat. The

other extremity of the tube is connected with the lower part of theboiler at F.

G is a steam-pipe to be connected with a steam-engine, s.

H is a steampipe that receives the escapesteam from the engine andpasses several times the length of the salting-vat, and finally emergestherefrom at I.

J is a discharging-pipe placed in the upper part of the boiler abovethefire-surface, which allows a portion of the purified brine to bedischarged into a conductor connected with the salting-vat.

K is a pipe connected with the forcepump, by which the boilers are fedwith crude brine. 1 L is a platform in the vat, placed suffi-.

ciently above the bottom to afford space for the steam-pipes for heatingand evaporating the chamber.

purified brine after it has been discharged from the boiler into thevat. A small space is left between the edge of the platform and the sideof the vat.

M is a paddle-wheel placed so as to revolve in or over a hole in theplatform L, the pad dies to revolve horizontally, and their upper edgescovered by a round plate, N. A bandwheel, 0, is placed upon the upperend of the shaft of the paddle-wheel, which is revolved by a band fromthe steam machinery.

P is a discharge-pipe for blowing off the contents of the boiler.

The operation of the above-described arrangement of apparatus is asfollows: The boiler is first filled with crude brine, and fire appliedin the arch R. Steam passes up through the tubes G into thesteam-chamber. As soon as the steam has suffieient pressure the engineis set in motion, and thereby also the force-pump for feeding theboilers, and the paddlewheel for causing a circulation of brine in thevat. The force-pump throws the brine into the steam-chamber through thepipe K, where it is heated by contact with the steam and falls into thebottom of the steam- The strength of the brine in the boiler isincreased by evaporation, and a quantity is thrown by ebullition overthe top of the tubes 0, and mixes the strong with the weak brine. Thisincreasing the strength of the brine in the steam-chamber causes thesepa ration of the impurities contained in the brine.

The brine of this locality and of most others contains such othermatters than salt as are usually termed impurities, viz; first, iron;second, sulphate of lime; third, muriate of lime, and fourth, muriate ofmagnesia. The first (iron) commences to be deposited shortly afterevaporation commences. The second (sulphate of lime) is deposited incrystalline form after a still further evaporation of the water from thebrine. The iron and sulphate of lime are separated or deposited frombrine before the crystallizing of the salt in all the ordinary processesof making salt. This is not the case with the muriates of lime andmagnesia, two deliquescing salts that remain in solution while the saltis crystallizing. A solution of these two salts forms what is called bythe workmen bitter water, and is known to greatly retard the process ofevapthan when cold.

or when subjected to the pressure of the atmosphere only. In the airwater can only be oration of water from the brine in the ordi- Thepressure in the boiler is regulated by a nary modes of salt-making. Insolar-works this bitter water floats upon the surface of the brine whenit (the brine) is of suflicient strength for salt to cyrstallize, andretards evaporation by its affinity for water. In works where the brineis boiled by artificial heat, the bitter water, combined with salt incrystals, adheres to the surface of the kettles or boilers and formswhat is known as bitterns, frequently found incrusted three inches inthickness, causing a rapid destruction of the boilers and lessening theeffects of the heat upon the water. Increasing the strength of brine byevaporation causes the separation and deposit of such in gredients asare contained in the same solution which have a less affinity for waterthan the salt. This separation is caused by depriving them of the waterwhich held them in solution, no more water remaining than is required orappropriated by the salt. In the methods of manufacture of salt now inuse-that is, v with open kettles and vatst-he salt crystallizes beforethe muriates of magnesia and lime,

and'the bitter water increases in amount as the boilers or vats arereplenished with brine until the whole has to be thrown away and thekettles cooled down to remove the bitterns, which is the most seriousdifficulty in the manufacture of salt.

According to authors, water will hold but a very little more salt insolution when heated This is true in open vessels heated to 212 andbrine to 226, consequently that is the limit to which the solution ofsalt can be carried.

My invention depends in part upon the dis covery that water may be maybe heated under pressure of steam to a sufficient extent,

and the evaporation carried so far before the crystallizing of the saltas to cause the separation or crystallization and deposit of themuriates of lime and magnesia, while the salt remains in solution. Ihave described such an arrangement as that the impurities will all becrystallized and deposited in a part of the boiler distant from thefire-surface. It is therefore obvious that if the salt is prevented fromadhering by reason of being kept in solution that no trouble can arisefrom incrustation. It contemplates the removal of the brine from theboiler after the impurities are all removed and deposited in thesettling chamber, the brine being perfeetlypure. N 0 other impuritiesthan those enumerated are found to any injurious extent in the brines ofthe United States. 7

By keeping the force -pump constantly at Work a current is kept upthrough the steamchamber, and the brine thus heated and mixed passesfrom the chamber into the large tube D and thence into the settlingtubes or chamber beneath the platform in the vat. 7 From there it passesinto the boiler near the bottom, and thus the boileris kept suppliedwith brine.

safety-valve. This process of evaporation is continueduntil the brineinthe boileris brought to near saturation. The current through. thesettling tubes or chamber is so slow as to allow the impurities todeposit before the brine passes into the boiler, where it comes incontact with the fire-surface. The steam raised in the boiler actuatesthe steam-engine, and then escapes into the heating-pipes extendedseveral times the length of the salting-vat and under the platform, theobject being to have sufficient length of heating-pipe to use all of theheat in the escape-steam for crystallizing the salt in the vat. Theforce-pump is made to throw brine into theboiler slightly faster than itis evaporated, by which means the boiler is filled and the steam-chamberis nearly filled with brine. As soon as it is ascertained that the brineis near the strength when salt would begin to form, the pipe J isopened, and all the brine contained in the boiler above thedischarge-pipe is blown out and into the salting-vat,where the saltrapidly crystallizes and falls upon the platform. This process offilling and alternately discharging brine from the boiler may becontinued until the settlingchamber is filled with impurities depositedfrom the brine, when the chamber may be opened and the impuritiesremoved.

The settling-chamber may be opened by a man-hole,which is usually madein boilers for the purpose of entering and removing incrustations ordeposits.

By the use of the platform in the vat the salt is arrested in itsdescent from the surface of the brine where crystallization commences,and consequently none is formed underneath the platform or in contactwith the iron steampipes; otherwise the salt would become stained bythejiron-rust.

The paddle-wheel serves when revolving to draw the brine from below theplatform to the upper surface. The paddle-wheel gives a centrifugalmotion to the water, and draws it up ward through the opening under thewheel, causing a rapid circulation of the water from the upper tothelower s'urface of the platform, and vice versa. by evaporation itpasses down past the edge of the platform, and is again heated by comingin contact with the steam-pipes. If more brine is purified in the boilerthan can be evaporated by the escape-steam in the vat, it may be drawninto open solar-vats and the crystallization completed.

This process may be continued under any pressure of steam that may berequired for actuating powerful steam machinery.

Heretofore the contact of such impurities as sulphate of lime, iron,muriate of lime,and

muriate of magnesia with the fire-surface of boilers has incrusted thesurface to such an extent as to greatly retard the evaporation of thebrine, to cause the rapid destruction of the iron, and require thefrequent cooling down of boilers for removing the bitterns or Afterbeing partially cooled incrustation. In the process described noincrustation forms on the fire-surface or within the boiler, and it maybe continued without interruption for months, or until thesettlingchamber is filled with impurities.

The crude brine is poured into the steamchamber of the boiler, in orderthat it may become highly heated by the steam, causing rapid evaporationand consequent increase of its strength, and by being mixed-with aportion of strong brine, which is thrown into the steamchamber from theboiler below, its strength is raised sufficiently to cause thecrystallizing or separation of its impurities while the salt remains insolution-that is, before the brine has reached the point of saturation.It is then passed into the settling-chamber, which may be made of anyconvenient form or size, where it is sufficiently free from the currentscaused by the fire in the boiler to allow the impurities to deposit. Theboiler is supplied with pure brine from the settling-chamber, and alarge portion may be drawn into the salt-ing-vat before crystallizationcommences. By the rapid working of the forcing-pump, the boilers areagain filled, the engine kept constantly in motion, and the escape-steamcompletes the evaporation in the salting-vat. In all other processes theimpurities adhere to the firesurface in the form termed bitterns, andgreatly retard the effect of the heat in the evaporation of the water,and render it necessary to frequently cool down the works to remove theincrustations. In the above process the impurities do not come incontact with with the fire-surface, and the fire may be run so as tohold the steam at a high pressure for months without interruption,giving the full power of steam, as in ordinary steam-boilers, theprominent object of the invention being the procuring of pure salt. Thebrine is brought to sufiicient strength in the steamchambers to causethe crystallization of all the impurities before it passes into thesettlingchamber, They remain mixed with the brine until it becomesquiet, when the crystals are deposited in the settling-chamber and thepure brine passes on into the boiler, where it comes in contact with thefire-surface. If, however, some of the impurities get into the boiler byreason of the process being hurried, they do not adhere to thefire-surface, but are found in the bottom of the boiler.

The apparatus described is to illustrate the process of purifying brineby artificial heat in such a manner as that neither the salt or itsimpurities become incrusted upon the firesurface of the boiler, and alsoa method by which boilers used in the manufacture of salt may be usedfor generating steam to propel the steam-engine for any desirable lengthof time without detriment from either salt or its impurities, and also amethod of preventing the contact of crystals of salt with iron pipes inthe bottom of salting-vats.

The process ofpurifying brine is indispensable to the use of brine insteam-engineboilers,

and the engine in turn works the pumps and paddle-wheel, by which thedescribed process of making pure salt is made complete.

What I claim as my invention, and desire to secure by Letters Patent,is-

1. Mixing weak with strong brine in the steam-chamber of the boiler forthe purpose described, and passing the brine thus mixed into a settlingapartment or chamber con nected with the lower part of the boiler, andthereby causing the separation and deposit of impurities from the brinebefore it comes in contact with the fire-surface of the boiler,substantially as set forth.

2. The method described of purifying brinevia, by evaporating it inclosed boilers to such an extent as to cause the separation and depositof its impurities while under pressure of steam, in eolnbinati on withvats for crystallizing the salt from the brine thus purified.

SAMUEL B. HOlVD.

XVitnesses:

GEORGE D. REDFIELD, Z. CHAS. Foo'r.

